Prime minister Tony Blair has told British Airways that its attempts to stop staff wearing the crucifix are a waste of energy.

The airline received high-profile criticism after it suspended check-in worker Nadia Eweida for refusing to remove a necklace bearing the cross.

She claimed this was religious discrimination as Sikhs and Muslims are allowed to wear haircoverings. And BA, which upheld its decision in an appeal hearing last week, was slated in a parliamentary motion signed by almost 100 MPs from all three major parties.

BA chairman Martin Broughton told Blair at the CBI annual conference that the government’s reaction was unjustifiable when it had the same uniform policy for the police force.

But Blair responded by advising Broughton to cave in to the pressure to allow staff to wear crosses.

“My frank advice is that there are some battles really worth fighting, and some battles really, really not worth fighting,” he said.

“I would say to you, get on the right side of that line. Some things arise in a certain way, and you are best to do the sensible thing. Do you know what I mean?”

Eweida has the right to a second appeal against her suspension, and BA has said it will review its uniform policy.